The present invention relates generally to methods and apparatus utilized in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides a hydraulic control system for downhole tools.
It would be desirable to be able to operate selected ones of multiple hydraulically actuated well tools installed in a well. However, it is uneconomical and practically unfeasible to run separate hydraulic control lines from the surface to each one of numerous well tool assemblies. Instead, the number of control lines extending relatively long distances should be minimized as much as possible.
Therefore, it would be highly advantageous to provide a hydraulic control system which reduces the number of control lines extending relatively long distances between multiple hydraulically actuated well tools and the surface. The hydraulic control system would preferably permit individual ones of the well tools to be selected for actuation as desired. The selection of well tools for actuation thereof should be convenient and reliable.
Furthermore, it would be desirable to provide methods of controlling operation of multiple well tools, and it would be desirable to provide well tools which may be operated utilizing such a hydraulic control system.
In carrying out the principles of the present invention, in accordance with an embodiment thereof, a hydraulic control system is provided which reduces the number of control lines extending relatively long distances to multiple well tool assemblies. Well tool assemblies and methods of controlling operation of multiple well tool assemblies are also provided.
In one aspect of the present invention, a control module is interconnected between a flowpath extending to a remote location, such as the surface, and flowpaths extending to multiple well tool assemblies. The control module provides fluid communication between the flowpath extending to the remote location and selected ones of the flowpaths extending to the well tool assemblies, so that corresponding selected ones of the well tool assemblies may be operated by pressure in the flowpath extending to the remote location.
In another aspect of the present invention, the control module is operated to select from among the flowpaths extending to the well tool assemblies by pressure in another flowpath connected to the control module. Yet another flowpath may be connected to the control module to provide a pressure differential used to operate the control module.
Various methods may be used to cause the control module to select from among the flowpaths extending to the well tool assemblies. In one disclosed embodiment, a ratchet device or J-slot mechanism is used to control displacement of a member of the control module. In another disclosed embodiment, a member of the control module is displaced against a force exerted by a biasing device, such as a spring or a compressed fluid.
In yet another aspect of the present invention, various well tool assemblies are provided, which may be operated by the disclosed hydraulic control systems. A variable flow area sliding sleeve-type valve is disclosed. The valve is operated by applying a series of pressures to an actuator thereof to incrementally displace a sleeve of the valve. As the sleeve displaces, the available area for fluid flow through the valve is increased or decreased.
Other well tool assemblies provided are a temperature sensor and a pressure sensor. Each of the sensors is operated by pressure in a flowpath thereof displacing a piston to a position in which the flowpath is placed in fluid communication with another flowpath. In the temperature sensor, the position of the piston corresponds to a known volume of a chamber in which a fluid exposed to the temperature is disposed. In the pressure sensor, the position of the piston corresponds to a known pressure differential between the flowpath and another flowpath exposed to the piston.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of a representative embodiment of the invention hereinbelow and the accompanying drawings.